Implement missing `OSWORD` calls

[bobbimanners]

auxmem.vdu.s:* OSWORD &09 - Read POINT
auxmem.vdu.s:WORD09        RTS
auxmem.vdu.s:* OSWORD &0A - Read character bitmap
auxmem.vdu.s:WORD0A        RTS
auxmem.vdu.s:* OSWORD &0B - Read palette
auxmem.vdu.s:WORD0B        RTS
auxmem.vdu.s:* OSWORD &0C - Write palette
auxmem.vdu.s:WORD0C        RTS
auxmem.vdu.s:* OSWORD &0D - Read gfx coords
auxmem.vdu.s:WORD0D        RTS

[bobbimanners]

Should try to do all the real work in main mem, since aux mem is tight.

OSWORD &09 is the only one used by BASIC, so I guess that is highest priority.